In the early portions of the Twentieth Century, there was a great feeling of desperation within the mental health community. Mental health hospitals were filled with thousands upon thousands of severely and chronically ill individuals, predominantly schizophrenic, for whom there were no viable means of therapy. Acting upon some erroneous data which indicated that there appeared to be an antagonism between schizophrenia and epilepsy, the Hungarian neuropsychiatrist, Meduna, attempted to induce seizures in schizophrenics by injecting oil of camphor intramuscularly. Within a year following his initial successful report of such use in the management of schizophrenia in 1935, news of the use of induced seizures for such a purpose spread around the world. A long, hoped for breakthrough had now occurred.
Producing seizures with the use of camphor, however, was by no means a pleasant or even reliable task. Even though camphor was almost immediately replaced by a pure pharmacologic preparation, pentylenetetrazol (or Metrazol), the use of this technique was still hampered by the presence of painful myoclonic contractions occurring prior to seizure onset. Occasionally, difficulty in inducing seizures at all, lack of predictability when the seizure would occur, and the possible presence of prolonged and recurrent seizure activity. Still, the therapeutic benefits of pharmacoconvulsive therapy, as it was called, clearly appeared to outweigh the difficulties.
Among those who were impressed by the early successes of pentylenetetrazol-induced seizures was the Italian neuropsychiatrist, Cerletti, who was at that time heavily involved in epilepsy research, using electrical stimulation to produce seizures in animals. Believing that therapeutic seizures in humans could be produced more easily and in a manner more tolerable to patients, Cerletti and his colleague, Bini, attempted to use their techniques clinically in 1937. The success of their initial report of such use in 1938 was heralded by psychiatrists as a significant improvement in the form of convulsive technique, and within one or two years had spread into clinical practice on a worldwide basis.
During the 1940's and throughout much of the 1950's electro-convulsive therapy (ECT) was a mainstay of psychiatric management of severe mental health disorders. As with any powerful new form of treatment, it was used on an extremely widespread basis. Over the course of this period of its use, it became clear that while ECT was occasionally useful at treating schizophrenia, its effects were even more beneficial in the management of severe affective disorders, particularly major depressive episodes. With the development of effective psychotropic alternatives for treating schizophrenia and affective disorders, beginning in the mid-1950's, the use of ECT began to decline.
At present, ECT is used sparingly. It is estimated that in the U.S., only three to five percent of psychiatric in-patients receive this treatment modally, and that between 30,000 to 100,000 patients per year are involved. Many psychiatrists believe that the decline in ECT utilization has now reached a turning point, in that there now appears to be a growing acceptance of its continual clinical role with respect to available therapeutic alternatives. Until the day comes when more effective and less toxic drugs or procedures become available, it is likely that ECT will continue to be used.
In their initial use of ECT, Cerletti and Bini were quite uncertain and apprehensive as to the proper means of stimulus dosage. Consequently, the first ECT machine was a rather complicated, ornate-appearing device, with numerous dials, buttons and controls. The type of electrical signal utilized by Cerletti and Bini was the sine wave, which is what is present in electrical sockets in homes and offices. As one would expect, this type of stimulus waveform was utilized because of its ready availability. If one looks on an oscilloscope, the household sine wave represents an undulating pattern of voltage or current, varying with time and repeating fifty to sixty times a second depending on the country.
Following the initial reports of actual stimulus parameters required to induce a seizure, in the absence of data pointing toward any direct electrical damage upon the organisms from such dosage levels, there was a drift among ECT device manufacturers to simpler and simpler devices. In some settings, this resulted in the use of stimulus electrodes which were plugged directly into a wall socket. In most cases, however, at least the presence of an "ON" button, along with a control for increasing or decreasing voltage or current, was present.
The early discovery that induced seizures were associated with confusion and amnesia, however, led researchers to try and experiment with the nature of electrical stimulus, under the assumption that more energy-efficient stimuli might have less detrimental side effects. By the mid- 1940's, Lieberson and colleagues had found that an interrupted stimulus pattern, consisting of brief, rapidly rising and falling pulses of electricity, separated by longer periods of electrical inactivity, offered the promise of producing seizures on a more efficient basis with seemingly less confusion and amnesia. Unfortunately, most practicing psychiatrists were either not aware of or were not impressed by this data. There was a feeling that the confusion and amnesia were either unimportant or perhaps even useful therapeutically. In addition, there were severe methodological problems with their early studies, as there were almost universally with investigations taking place during this time period. Accordingly, the use of the sine wave stimulus, at least in the U.S., continued to be extremely widespread into the 1970's.
In the mid-1970's the late psychiatrist and prominent ECT researcher, Paul Blachley, decided that, given the degree of concern over memory deficits which had arisen during the ongoing controversy over unilaterally, nondominant versus bilateral electrode placement, an attempt should once more be made to offer an option of brief-pulse stimulus waveform with ECT devices. In addition, Blachley felt that this "optimal" device should also incorporate the capacity of monitoring both EEG and ECG; and should offer the user a clear means to test the safety of the electrical circuit before delivering the stimulus; and finally, that it should be able to offer the ability to allow careful titration to individuals' seizure thresholds. After design and testing efforts, this device, which was known as the MECTA (Monitored Electro-Convulsive Therapy Apparatus) went on the market in 1977, and readily grew in popularity over the following years.
Based on a number of developments in the research literature, and comments and suggestions by psychiatrists using ECT devices, a new generation of MECTA devices was placed on the market. This new generation included the SR and JR models manufactured and sold by MECTA Corporation, of Lake Oswego, Oreg. Although this new generation of ECT devices was an improvement over existing devices in terms of safety, effectiveness and ease of use, there were still additional improvements to be made in all of these areas.
The SR and JR models include two safety features. The first feature uses a "self-test." Despite its name, the "self test" does not test the device itself but instead measures the static patient impedance prior to application of an ECT stimulus. The clinician instigates this test by pushing a self-test button on the device after the ECT electrodes are positioned on the patient. The ECT device then measures the impedance running from the ECT device through an ECT electrode, the patient, the other ECT electrode, and back to the device. During the self-test, the device passes a minute current through the circuit. These models measure the impedance by measuring the voltage produced across the circuit and dividing that measured voltage by an assumed current level. The calculated static impedance is then compared to a predetermined range of static impedances. If the calculated static impedance is within that range, the self-test passes. Otherwise, the self-test fails.
If the static patient impedance is outside the acceptable range, the device inhibits delivery of an ECT stimulus unless an "impedance override" button is pressed. The impedance override button allows clinicians to bypass the self-test failure and engage a stimulus delivery sequence where the extreme static impedance value is due to a peculiar patient's characteristics.
The SR and JR models from MECTA also allow the clinician or other technician to verify that the device is operating within their specified tolerances. This is accomplished by connecting the stimulus output of the device to an external resistor substitution box, i.e., a "dummy" load. A stimulus sequence can then be applied to the dummy load and the resulting signal's characteristics can be measured with the use of an external oscilloscope whose leads are applied across the resistor dummy load. The clinician or technician can then compare the measured signal characteristics as displayed on the oscilloscope with the parameter settings specified by the dial settings on the device. In this way, the frequency, pulse width, duration and energy specifications can be verified. If the device turns out to be out of range or out of specification, the device can then be returned to the manufacturer for repair or recalibration.
Although the self-test and the calibration test are useful, they do not go far enough. The main problem with both of these tests is that they are conducted prior to the ECT treatment sequence and not during the treatment itself. Thus, if one or more of the parameters (current, voltage, pulse width, frequency or duration) were to drift out of range during an actual treatment, this condition would not be detected until the next calibration test. Moreover, the self-test checks only a single parameter, i.e., static impedance, and none of the other parameters which determine the amount of energy actually delivered to the patient.
The MECTA SR and JR devices do display an estimated energy delivered to the patient during treatment. This energy, however, is an estimate based on several assumed parameter values. As is known in the art, energy is a function of voltage, impedance, and time or duration. In the MECTA devices, only the voltage and impedance are measured and the time or duration is assumed based upon the duration setting on the front panel. Thus, if the actual duration of the applied ECT treatment sequence is different than that specified on the front panel, the estimated energy will not equal the actual delivered energy. As a result, the clinician can be misled as to the actual delivered energy.
Accordingly, a need remains for improved parameter monitoring both prior to and during ECT treatment.